1.5.2 Conforming Programs

Code conforming with the requirements of this standard shall adhere to the
following:

1. Conforming code shall use only those features of the
language syntax and semantics that are
either specified in this standard
or defined using the extension mechanisms
specified in the standard.

2. Conforming code may use
implementation-dependent features and values,
but shall not rely upon
any particular interpretation of these features and values
other than those that are discovered by the execution of code.

3. Conforming code shall not depend on the consequences
of undefined or unspecified situations.

4. Conforming code does not use any constructions
that are prohibited by the standard.

5. Conforming code does not depend on extensions
included in an implementation.